net/lapb/lapb_timer.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      LAPB release 002
   4  *
   5  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   6  *
   7  *      History
   8  *      LAPB 001        Jonathan Naylor Started Coding
   9  *      LAPB 002        Jonathan Naylor New timer architecture.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/socket.h>
  17 #include <linux/in.h>
  18 #include <linux/kernel.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/timer.h>
  21 #include <linux/string.h>
  22 #include <linux/sockios.h>
  23 #include <linux/net.h>
  24 #include <linux/inet.h>
  25 #include <linux/skbuff.h>
  26 #include <net/sock.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/fcntl.h>
  29 #include <linux/mm.h>
  30 #include <linux/interrupt.h>
  31 #include <net/lapb.h>
  32
  33 static void lapb_t1timer_expiry(struct timer_list *);
  34 static void lapb_t2timer_expiry(struct timer_list *);
  35
  36 void lapb_start_t1timer(struct lapb_cb *lapb)
  37 {
  38         del_timer(&lapb->t1timer);
  39
  40         lapb->t1timer.function = lapb_t1timer_expiry;
  41         lapb->t1timer.expires  = jiffies + lapb->t1;
  42
  43         lapb->t1timer_stop = false;
  44         add_timer(&lapb->t1timer);
  45 }
  46
  47 void lapb_start_t2timer(struct lapb_cb *lapb)
  48 {
  49         del_timer(&lapb->t2timer);
  50
  51         lapb->t2timer.function = lapb_t2timer_expiry;
  52         lapb->t2timer.expires  = jiffies + lapb->t2;
  53
  54         lapb->t2timer_stop = false;
  55         add_timer(&lapb->t2timer);
  56 }
  57
  58 void lapb_stop_t1timer(struct lapb_cb *lapb)
  59 {
  60         lapb->t1timer_stop = true;
  61         del_timer(&lapb->t1timer);
  62 }
  63
  64 void lapb_stop_t2timer(struct lapb_cb *lapb)
  65 {
  66         lapb->t2timer_stop = true;
  67         del_timer(&lapb->t2timer);
  68 }
  69
  70 int lapb_t1timer_running(struct lapb_cb *lapb)
  71 {
  72         return timer_pending(&lapb->t1timer);
  73 }
  74
  75 static void lapb_t2timer_expiry(struct timer_list *t)
  76 {
  77         struct lapb_cb *lapb = from_timer(lapb, t, t2timer);
  78
  79         spin_lock_bh(&lapb->lock);
  80         if (timer_pending(&lapb->t2timer)) /* A new timer has been set up */
  81                 goto out;
  82         if (lapb->t2timer_stop) /* The timer has been stopped */
  83                 goto out;
  84
  85         if (lapb->condition & LAPB_ACK_PENDING_CONDITION) {
  86                 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
  87                 lapb_timeout_response(lapb);
  88         }
  89
  90 out:
  91         spin_unlock_bh(&lapb->lock);
  92 }
  93
  94 static void lapb_t1timer_expiry(struct timer_list *t)
  95 {
  96         struct lapb_cb *lapb = from_timer(lapb, t, t1timer);
  97
  98         spin_lock_bh(&lapb->lock);
  99         if (timer_pending(&lapb->t1timer)) /* A new timer has been set up */
 100                 goto out;
 101         if (lapb->t1timer_stop) /* The timer has been stopped */
 102                 goto out;
 103
 104         switch (lapb->state) {
 105
 106                 /*
 107                  *      If we are a DCE, send DM up to N2 times, then switch to
 108                  *      STATE_1 and send SABM(E).
 109                  */
 110                 case LAPB_STATE_0:
 111                         if (lapb->mode & LAPB_DCE &&
 112                             lapb->n2count != lapb->n2) {
 113                                 lapb->n2count++;
 114                                 lapb_send_control(lapb, LAPB_DM, LAPB_POLLOFF, LAPB_RESPONSE);
 115                         } else {
 116                                 lapb->state = LAPB_STATE_1;
 117                                 lapb_establish_data_link(lapb);
 118                         }
 119                         break;
 120
 121                 /*
 122                  *      Awaiting connection state, send SABM(E), up to N2 times.
 123                  */
 124                 case LAPB_STATE_1:
 125                         if (lapb->n2count == lapb->n2) {
 126                                 lapb_clear_queues(lapb);
 127                                 lapb->state = LAPB_STATE_0;
 128                                 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
 129                                 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
 130                                 goto out;
 131                         } else {
 132                                 lapb->n2count++;
 133                                 if (lapb->mode & LAPB_EXTENDED) {
 134                                         lapb_dbg(1, "(%p) S1 TX SABME(1)\n",
 135                                                  lapb->dev);
 136                                         lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 137                                 } else {
 138                                         lapb_dbg(1, "(%p) S1 TX SABM(1)\n",
 139                                                  lapb->dev);
 140                                         lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 141                                 }
 142                         }
 143                         break;
 144
 145                 /*
 146                  *      Awaiting disconnection state, send DISC, up to N2 times.
 147                  */
 148                 case LAPB_STATE_2:
 149                         if (lapb->n2count == lapb->n2) {
 150                                 lapb_clear_queues(lapb);
 151                                 lapb->state = LAPB_STATE_0;
 152                                 lapb_disconnect_confirmation(lapb, LAPB_TIMEDOUT);
 153                                 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
 154                                 goto out;
 155                         } else {
 156                                 lapb->n2count++;
 157                                 lapb_dbg(1, "(%p) S2 TX DISC(1)\n", lapb->dev);
 158                                 lapb_send_control(lapb, LAPB_DISC, LAPB_POLLON, LAPB_COMMAND);
 159                         }
 160                         break;
 161
 162                 /*
 163                  *      Data transfer state, restransmit I frames, up to N2 times.
 164                  */
 165                 case LAPB_STATE_3:
 166                         if (lapb->n2count == lapb->n2) {
 167                                 lapb_clear_queues(lapb);
 168                                 lapb->state = LAPB_STATE_0;
 169                                 lapb_stop_t2timer(lapb);
 170                                 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
 171                                 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
 172                                 goto out;
 173                         } else {
 174                                 lapb->n2count++;
 175                                 lapb_requeue_frames(lapb);
 176                                 lapb_kick(lapb);
 177                         }
 178                         break;
 179
 180                 /*
 181                  *      Frame reject state, restransmit FRMR frames, up to N2 times.
 182                  */
 183                 case LAPB_STATE_4:
 184                         if (lapb->n2count == lapb->n2) {
 185                                 lapb_clear_queues(lapb);
 186                                 lapb->state = LAPB_STATE_0;
 187                                 lapb_disconnect_indication(lapb, LAPB_TIMEDOUT);
 188                                 lapb_dbg(0, "(%p) S4 -> S0\n", lapb->dev);
 189                                 goto out;
 190                         } else {
 191                                 lapb->n2count++;
 192                                 lapb_transmit_frmr(lapb);
 193                         }
 194                         break;
 195         }
 196
 197         lapb_start_t1timer(lapb);
 198
 199 out:
 200         spin_unlock_bh(&lapb->lock);
 201 }